This invention relates to manufacture of low viscosity hydrogenated butadiene polymers having terminal functional groups and use of the low viscosity polymers to make coatings and other high molecular weight polymers.
Anionic polymerization of conjugated dienes with lithium initiators, such as sec-butyllithium, and hydrogenation of residual unsaturation has been described in many references including U. S. Pat. No. Re. 27,145 which teaches a relationship between the amount of 1,2-addition of butadiene (35% to 55% ) and the glass transition temperatures of the hydrogenated butadiene polymers.
The termination of living anionic polymers to form functional end groups is described in U.S. Pat. Nos. 4,417,029, 4,518,753, and 4,753,991. Of particular interest for the present invention are terminal hydroxyl, carboxyl, phenol, epoxy, and amine groups.
For unsaturated 1,3-butadiene polymers it is known that low 1,2-addition is necessary to obtain low viscosity as taught in U.S. Pat. Nos. 4,518,753 and 3,652,732. However, when these polymers are hydrogenated they are crystalline solids. Such a crystalline polymer is available from Mitsubishi and is designated POLYTAIL H polymer which has a melting point of 72.degree. C.
The hydrogenated butadiene polymers are non-crystalline when the 1,2-addition of butadiene is above 30% as described in U.S. Pat. No. 4,020,125. The non-crystalline hydrogenated butadiene polymers are viscous liquids at low molecular weights as described in U.S. Pat. Nos. 4,866,120 and 4,020,125. POLYTAIL HA polymer produced by Mitsubishi and NISSO GI-2000 polymer produced by Nippon Soda are commercial examples of low molecular weight hydrogenated butadiene polymers which have terminal functional groups and 1,2-addition of about of 84%.
It is an object of the present invention to provide hydrogenated butadiene polymers having terminal functional groups and low viscosity at room temperature. It is also an object of the invention to use the low viscosity polymers to make coatings and other high molecular weight polymers.